It is well known that production from oil and gas wells can suffer due to the build-up of fluids at the bottom of the well. See e.g., U.S. Pat. No. 6,148,923, which is incorporated herein by reference. Various methods and devices have been developed to remove those fluids so as to improve the well's productivity.
One such device is known as a plunger, of which there are many variants known to those skilled in the art. For example, an auto-cycling plunger operates as follows: (1) it is dropped into the well (at the well's surface), (2) it free-falls down the well until it stops upon impact with the bottom of the well, and (3) it thereafter is caused (by pressure in the well) to travel back toward the surface of the well, pushing a “load” of liquid above it for removal at the well's surface by a lubricator assembly. The plunger then is allowed to repeat that cycle, thereby ultimately removing enough fluid from the well to improve its production.
A number of problems have arisen from the use of prior art plungers. For example, due to the typically great distance between the surface and bottom of a well, and high pressures within the well system, the plunger travels at a great rate of speed when it is received by the lubricator. Impacts between the plunger and the lubricator can be violent; they often are so violent that damage occurs (either immediately or over time due to repeated use) to lubricator. As another example, the repeated cycling of the plunger causes at least certain of its parts eventually to wear out.
For example, a prior art lubricator includes a main body configured to receive the plunger. The main body may include a spring or catcher assembly for dampening the impact between the lubricator and the plunger. Fluids raised by the plunger may be ejected from the main body through one or more ports. In prior lubricator assemblies, the ports are pipes, flanges, threaded connectors, or the like that are welded over a hole in the main body.
The lubricator experiences high fluid pressures when the fluids are compressed at the lubricator by the plunger because of the violent impacts between the plunger and the lubricator assembly. Further, vibrations are experienced by the lubricator and connected assemblies each time the plunger impacts the lubricator. Consequently, wear and tear during normal operation of the plunger lift assembly can be experienced by all components of the system, and in particular by the lubricator. A common failure point of the lubricator component is the junctions or welds between the ports and the main body. The high pressures may cause leaks at the junctions, or vibration may degrade the welds over time, particularly when heavy pipe or other components are attached to the ports.